Motor control



Dec. 13, 1927.

IN V EN TOR.

N. L. MORTENSEN MOTOR CONTROL Filed June 8. 1921 ATTORNEY.

Patented en. 13, 1927.

NIEIZS L. MORTENSEN, OF MILWAUKEE, WISCONSIN, ASSIGNQR TO THE GU'EJZLER-HAM- HER MFG. 00., O1! MILWAUKEE, WISGGNESILN, A @GRPQ'EQATIQN OF vrrsoorrsrn.

moron 'oonraon.

a plication flied m le a, rear. serial no. erases.

present invention has among its ob'ects that of providing a modified and improved method of motor control enabling such ac- 1 tion. 1

Another object is that of providing such a method whereby the motor speed in either direction may be automatically determined in accordance with the load as ascertained 2 during operation of the motor in a given direction.

Another object is that of providing a method of control of motors employed in the aforementioned and similar service wherein provision is made for automatic preselecting during hoisting, of control conditions suitable for lowering the load hoisted and enabling subsequent subjection of the control for lowering to'infiuence of the preselected conditions while also enabling establishment and maintenance of other control conditions not. involving higher operating speeds.

Another object is that of providing apparatus for performance of, the foregolng as methods.

Another object is that of providing. a dynamic braking controller for a hoisting motor enabling preselection of the speed of movement of the load in one or in both di- 40 motions in accordance with the value of the load as ascertained during movement ina given direction.

(lther objects and advantages will hereinalter appear.

ln the accompanying drawing, wherein are illustrated certain embodiments otlthe invention in its physical aspects;

.Figure l is a diagrammatic view illustrating one or" the "terms thereof;

Figs. 3 and 5 are similar diagrammatic posed to effect preselection of the control conditions to be imposed, particularly during lowering, in accordance with effects proportional to the load to be handled, as ascer-' tained during hoisting of the load. Thus, it is proposed in addition to the usual control lectures, to provide for further speed regulation of the motor, as by field variation, and also to provide for enactment or non-enactment of such special control, dependent upon the value of the load hoisted and also subject to voluntary selection and preselection.

In practice one or more seriesrelays subjected to the motor current, or to another agency proportional to the motor load, may be employed for automatically determining the action as well as the extent of action of the special speed control instrumentalities employed, whereas the usual drum or other controller employed is provided, with additional cont-acts afiording voluntary control of such instrumentalities subject, however, to dominant control by the load responsive means.

Referring to Figs. 1 and 2 of the drawing, the same illustrate a reversible compound motor to he supplied with current from lines L,.llj and comprising an armature A, a series field F and a shunt field F, a brake releasin coil B being arranged to be connected in series with series field F. Steps R to R of accelerating resistance and an additional step R of dynamic braking resistance are also provided for the motor, while a reversing drum controller serves to commutate the various circuit connections in a well known manner to provide for operation or the motor in reverse directions for hoisting and lowering respectively, also to provide for dynamic lowering of overhauling loads and to maintain the dynamic connections when moved to oil position, and also for deenergization oil the bralrereleasing the off and the final hoisting and lowering controller to line L positions. Said rheostat is provided with automatic setting or ad usting means comprising a ratcheting device 0t known construction havin operating solenoids 10 and 11 adapted selectively to effect progressive movement of the rheostat arm in opposite directions -tor increasing and decreasing the value of the rheostat resistance to be connected in circuit.

A pair of series relays l2 and 18, having their energizing coils subjected to the motor current are adapted to control energization of ratcheting solenoids 10- and 11 respectively, the energizin circuits of the latter being subjected to urther control by the drum controller. The series relay 12 is normally closed and is calibrated to respond at a lesser value of the motor current than that at which the normally open relay 13 is adapted to respond.

The drum controller is adapted to eifect the usual control of the atoredescribed motor, including reversal, dynamic braking and lowering all in a manner wall understood by those skilled in the art, whereas movement of the drum controller to either of ts extreme positions serves to provide the additional effects now to be described.

Assuming operation of the motor under the control of the drum controller for hoistng the empty crane hook or the hook carrymg a relatively light load, the series relay 13 will remain unresponsive and the series relay 12 will likewise either fail to respond or responding will effect reclosure of its contacts upon or prior to movement of the drum controller to its finalhoisting position. Un der these conditions the energizing circuit of ratcheting solenoid 11 is uncompleted whereas the energizing circuit or" solenoid 10 is completed from line L through said series relay 12 to and through said solenoid coil thence through contact n of the drum The ratcheting mechanism now acts to increase the effective value of the rheostat resistance thereby weakening the motor shunt field and ermitting further acceleration of the hoisting action, 1t being recalled that the rheostat is in circuit in the assumed position of the drum.

Such adjustment of the rheostat will continue until the resultant weakening of the shunt field permits a sufiicient flow of current in the motor circuit to effect response of l I series relay 12 whereu on the circuit of soleterminating the adweakening action to a value suificient to effect response of series relay 13 the energizing circuit of the ratcheting solenoid 11 is completed, thereb effecting reverse adjustment .of the -r eostat with consequent strengthening of the shunt field, and such rheostat adjustment will continue until the resultant value of the motor current is such as tomaintain both series relays open, the corresponding setting of the rheostat being thus pro-selected for influencing the control d t ring lowering.

During hoisting of a relativelq. heavy load such that both series relays are held up while the drum controller occupies its final hoisting position obviously the ratcheting coil 11 is energized and the coil 10 is unenergized, whereby the rheostat 9 is adjusted to-strengthen the shunt field until the motor current is reduced toa value such as to permit opening of relay 13 while maintaining the relay 12 likewise open, compensation for possible over-regulation being effected in a manner similar to that just described but in positioning of the drum in said final lowermg position, however, the rheostat 9 is in sorted in the shunt'field circuit thereby effecting a degree of fieldweakening determined by the aforedcscribed pro-setting of the rheostat, whereby obviously the final H ll Ill)

lowerin speed is determined by the value of the load asascertained during hoisting. It is of course to he understood that the controller may be modified to provide for insertion of the field rheostat at any desired point.

Figs. 8 and 4 illustrate a modified con troller adapted to provide a similar character of control of a series motor.

In this instance an additional step R of resistance is arranged to' he connectedin,

series with the motor field upon movement of the drum controller to its extreme position for lowering under conditions of light load. i

An electro-responsive switch 20 serves to control exclusion and inclusion of said resistance-in circuit. The energizing circuit of switch 20 is controllable jointl by means of contact of the drum contro ler and by an electro-responsive presetting switch 21, and the circuit of said latter switch is controllable jointly through contact n of the drum controller "and a series relay 22 subjected to the motor current. Said switch 21 is further adapted to maintain itself closed independently of said series relay but subject to control by the drum controller.

Thus, upon movement of the drum controller to its extreme position for hoisting, it

the load and motor current conditions are such as toeflect opening of series relay 22 the controller will provide only'the usual control features. However, under conditions of light load'such as to permit closure of series relay 22 the closing circuit of switch 21 is established from line L through the coil of said switch 2.1 and through said series relay 22 to drum contact n and thence to line L Switch 21 thereupon closes presetting the device to provide thespecial high lowering speed. [also said switch upon closing maintains itself by way of its upper set of cont-acts and drum contact 0, which lat-. ter contact is energized for all positions of the drum except the final hoisting position. Thus, following closure of switch 21 the same can be permitted to open only, by placing the drum in such final hoisting position struction.

with concurrent opening of series relay 22.

The aloredescribed closure of switch 21 is without influence upon the control efiected except upon throwing the drum to the final lowering position whereupon the circuit of the resistance R is arranged to be connected in parallel with the motor field l instead at in series therewith as in the preceding core A normally open QlQGiDlG-IQSPOIlSlVQ switch 20 serves when closed to complete such cir= cuit including said resistance R in parallel with the motor field, whereas a presetting switch 21 serves in conjunction with the series relay 22 and the drum -.controller to control the opening and closing action of said switch 20.

Upon movement of the drum controller to its final hoisting position under conditions or": heavy load and correspondingly heavy motor current the series relay 22 is maintained open and prevents closure of either switches 20 or 21, thus restricting the action of the controller to that ordinarily provided. However, under conditions of light load such as to permit closure of the series relay upon final hoisting positioning of the drum the closin circuit of switch 20 is completed from line L through the coil of said switch through series relay 22 and contact n of-the drum controller to line I]. Said switch thereupon closes connecting resistance R in parallel with the motor field circuit as described and also by means of its lower set of contacts serves to complete a-piclrup circuit for switch 21 from line L through the coil of said switch 21*- and through the lower set of contacts of switch 20 to drum contact 0 and thence to line L Said switch 21 thereupon closes and maintains itself by means of its own upper contacts and through contact p of the drum controller, said latter contact being energized for all positions of the drum controller except the final hoisting position, and the atoredescribed maintaining circuit bein independent of series relay 22. Said switc 21' upon closure thereof also serves by means of its lower set of contacts to establish partial circuit connections for the closing coil of switch 20*, subject to completion independently ot the position of series relay 22 upon movement of the drum controller to its final lowering position. v

Upon movement of thedrurn controller out of its final hoisting position the switch 20 is adapted to open thus opening the resistance shunt around the motor held and the character of the control efiected is there fore uninfiuenced by the atoredescribed special features except upon movement of the drum to either its final hoisting or final lowering position. lln either of these positions said switch 20 is closed for re-establishment of such field shunt, closure of such switch 20 in the final hoisting position of the drum.

being dependent either upon closure of the series relay 22 or upon continued closure of switch 21*, whereas closure of said switch 20 in the final lowerin position of the drum is dependent absolute y upon presetting and continued closure of the switch 21'.

Thus, obviously this type of controller provides for acceleration of the controlled motor by means of the field shunt during hoisting as well as during lowering. However, if desired the controller may by obvious expedients be modified to restrict such actioh to conditions of lowering. Similarly the control provided by the construction of 1. may be modified for so restricting theaction of the special acceleration features provided by merely increasing the len th of the drum hoist segment co-operating with contact 0 suficiently to efiect short-circuiting Again the construction illustrated in Fig.

. 3 may readily be modified to afford the higher motor speeds for hoisting as well as for lowering, whereas the field rheostat together with its 0 crating means as illustrated in Fig. l may, if desired, be substituted in the control schemes illustrated in Figs. 3 and 5, while said latter constructions may each be provided with several steps of field resistance having individual controlmeans. Also, if desired, the structure of Fig. 5 may be modified by subjecting the control of the field paralleling resistance to different con tactors and series relays under conditions of hoisting and lowering respectively, thereby permitting attainment of a higher motor speed for lowering than that permitted for hoisting. Finally it is obvious that the full electrical control aforedescribed may be substituted wholly or in partby mechanical devices associated with and operable by the drum controller for attainment of the effects aforedescribed.

The various circuit connections commutated by the individual forms of controller are illustrated in the simplified diagrams of Figs. 2, 4 and 6 whereas the sequence of operation of the various controller parts is depicted in the corresponding complete diagrams.

What I claim as new and desire to secure by Letters Patent is:

1. The method of control of a motor to be subjected cyclicly to conditions of positive and negative load, which comprises comparing the value of the load during a given portion of the operating cycle with a standard value and pre-arranging for control of the motor during a subse uentportion of its operating cycle in accord gree of departure of the load from such standard value.

' 2. The method of control of a motor to be operated in cycles and each cycle including subjection of the motor sequentially to cond1t1ons of positive and negative load which com rises e the oad during a given earlier portion of the operating cycle with a. standard value, prearranging control conditions for the motor m' accordance with the result of such comparlson and enacting the prearranged control during a subsequent portion of the same 0 cle.

3. T e method of control of a reversible 1 motor to be operated in'c cles and each cycle to include subjection of t e motor sequentially to conditions of positive and negative load, which comprises ascertaining the effect of the load on the power consumption of the motor within a single '0. ole and prearranging'maccordance Wlth e ascertained value the control conditions to be applied to the ance with the deectrically comparing the value of vmotor within the same "cycle but under reverse 0 crating conditions.

4. T e method of control of a reversible motor to be operated in cycles and each cycle to include subjection of the motor, sequentially to conditions of positive and negatlve load, which comprises ascertaining the effect of the load on the power consumption of the motor Within a single cycle, prearranging the character of control to be subsequentl .applied to the motor in accordance with t e ascertained value and applyin ranged control to the motor wiiile subjected to negative load conditions of the same operating cycle. I

5. The method of control of a reversible motor to b'eoperated in cycles and each cycle to include subjection of the motor sequentially to conditions of positive and negative load, which comprises detecting variations in load through the effect thereof on the power consumption of the motor within a sin le cycle, prearranging in accordance with suc variations the character of a control to be subsequently applied to the motor and enacting the prearranged control during subsequent voluntarily? determinable periods within the same cycle.

6. The method of control of a reversible motor to be operatedin c cles and each cycle to include subjection of t e motor sequentially to conditions of positive and negative load, which comprises detecting variations in positive load through ascertaining the effect thereof upon the power consumption of the motor within a singl cycle, prearranging in accordance with such variations the character of a control to be subs uently applied to the motor and applying t lie reselected control to the motor during a su sequent voluntarily determinable period during operation of the motor in either direction within the same cycle.

the prear- 7. The method of controlling the speed of operated cyclicly under difierentload conidltions, of speed controlling means having tor to be operated cyclicly for hoistihg and or subject to influence thereby according to the positioning of said master controller. 9. The combination with a reversible moloweriug loads of different values, of speed controlling means having automatic means to set the same according to the -value of the load being hoisted to afford preset control 'for lowering and a master controller acting according to the positioning thereof to render said preset control means etlective or inefiective during lowering,

10. The combination with a reversible mo- .tor to be operated in cycles and each cycle to include subjection of the motor sequentially to condi-tions of positive and negative load, of control means for the motor comprising means for ascertaining the eiifect of the load on the power consumption of the motor within a single cycle, and meansfor utilizing the ascertained effect in prearranging control conditions for the motor within the same cycle but under reverse operating conditions.

Ill. The combination with reversible motor to be operated in cycles and each cycle to include subjection of the motor sequentially to conditions of positive and negative load, of control means for the motor comprising means for ascertaining the effect of the load on the power consumption of the motor Within a single cycle, means for utilizing the ascertained value in prearranging the character of -control to be subsequentl applied to the motor, and means for app ying the prearranged control of the motor while subected to negative load conditions of the same operating cycle.

12. The combination with a reversible motor to be operated in cycles and each cycle to include subjection or the motor sequentially to conditions of positive and negative load,

' of control means for the motor comprising means for means for detecting variations in load through the eilect thereof on the power consumption of the motor within a single cycle, rearranging in accordance with such variations the character of a control to be subsequently applied to the motor, and means for enacting the prearranged control during subsequent voluntarily determinable periods within the same cycle.

13. 'lhecombination with a reversible motor to be operated in cycles and each cycle to include subjection ot the motor sequentially to conditions of positive and negative load, of control means for the 'motor comprising means for detecting variations in positive load through the eilect thereof upon the power consumption of the motor within a single cycle, means for prearrangin in accordance with suchvariations the caracter of a control to be subsequently applied to the motor, and means for appl ing the preselected control to the motor dining also adapted to utilize the'efiect oil such subsequent voluntarily determinable period during operation of the motor in either direction within the same cycle.

14. The combination with a motor to be subjected to positive loads which vary from one another and to negative loads each sub stantially similar in magnitude to a corresponding positive load, of speed controlling means for the motor comprising means for detecting variations in the positive load through the effect thereof upon the value of the motor current, means for prearrn ing in accordance with such variations the 0 aracter of control to be subsequently enacted, and means for thereafter enacting the prearranged control under conditions ot corresponding negative load.

.15. In a control system wherein motors are subjected to positive and negative loads, the

combination with means to'preselect control,

conditions for the control of a negative load in accordance with the motor current under conditions of positive load, of means for edecting enactment oil the control conditions so preselected.

16. In a hoisting controller tor motors, the combination with means for varying the motor field excitation inaccordance with the value of the load being hoisted, oil control means for said tormer means comprising a series relay to be subjected to the motor cur= rent, a drum controller having parts adapt ed to provide for operation or said field varying means but only following a given action of said series relay, and means for controlling the motor field excitation during the combination with electroresponsive speed varying meansfor the motor, of control means for said former means subjected to electrical influence in accordance with the positive load upon the motor, and voluntary control means for subjecting said speed varying means to control by said second mentioned means, said voluntary control means being noe tive load influence under conditions of negative load,

18. In a control system wherein motors are subjected to positive and negative loads,

the combination with adjustable speed con trol means for the motor, of means for antoinatically efiecting adjustment of said for mermeans in accordance with the positive load upon the motor, and manually oper- Hill? Elli) the motor, of means subjecting said former control means and further adapted to utilize means to series relay control for varying the during lowerin the motor field adjustment motor field in accordance with the value of effectediduringioisting. I 10 the motor current during hoisting and a In witness whereof, I have hereunto sub: 5 drum controller having parts adapted to conscribed my name.

trol the operation of said power operated a means sub ect to control by said series relay NIELS L. MORTENSEN. 

